The distance between the Sun and the Earth is not constant because Earth's orbit is elliptical.

Here's the breakdown:

* Average distance: 149.6 million kilometers (93 million miles)

* Closest point (perihelion): 147.1 million kilometers (91.4 million miles)

* Farthest point (aphelion): 152.1 million kilometers (94.5 million miles)

Converting to millimeters:

* 1 kilometer = 1,000,000 millimeters

* 1 million = 1,000,000

Therefore, the average distance in millimeters is:

* 149.6 million kilometers * 1,000,000 millimeters/kilometer = 149,600,000,000,000 millimeters

The closest and farthest distances can also be converted to millimeters using the same method.